Histopathological study on pulpal response to restorative composite resins and their ingredients.

This study was conducted in monkeys (M. fuscata) to investigate the pulpal responses to the dental composites, uncured resin pastes and their ingredient monomer pastes; Clearfil FIT (C1FII), PhotoClearfil A (PhC1A), TEGDMA, Bis-GMA and UDMA. Histopathological changes in the pulp and the presence of bacteria on the dentinal wall were examined periodically throughout the 180 days after insertion. The findings were as follows:1. The C1FII and PhC1A groups showed slightly greater pulpal responses than the zinc oxide-eugenol cement (ZOE) group, having a slightly greater irritation dentin formation in the latter period without any severe histopathological change.2. At the initial stage, the pulpal response to the uncured C1FII pastes was greater than that to the cured C1FII. The pulpal response to the light-cured PhC1A was smaller than that without light-curing. In the latter period, slight inflammatory changes were observed with the uncured pastes in spite of the large amount of irritation dentin formation.3. The pulpal damages by the TEGDMA, Bis-GMA and UDMA pastes were greater than those in the other groups at the initial stage. This group showed a large amount of irritation dentin formation accompanied by slightly greater inflammatory changes than those by the uncured resin pastes in the latter period.4. The bacterial penetration into the dentinal tubles further increased the inflammatory responses.